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CEMC Gauss (Grade 8), 2014

Algebra Difficulty 1.4 Junior Find the answer Canada

The ratio of the number of girls to the number of boys in a class of 24 students is $3:5$ . How many fewer girls than boys are in the class?

Pick one

Solution

In the table below, each of the five expressions is evaluated using the correct order of operations.

Expression	Value
(A) $3-4\times5+6$	$3-20+6=-17+6=-11$
(B) $3\times4+5\div6$	$12+5\div6=12+\frac 56=12\frac 56$
(C) $3+4\times5-6$	$3+20-6=23-6=17$
(D) $3\div4+5-6$	$\frac 34+5-6=5\frac 34 -6=\frac{23}{4}-\frac{24}{4}=-\frac 14$
(E) $3\times4\div5+6$	$12\div5+6=\frac{12}{5}+6=2\frac 25+6=8\frac 25$

The only expression that is equal to 17 is $3+4\times5-6$ , or (C).

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